THE SECRET OF AERIAL
ARCHAEOLOGY

It's simply Perspective: the distant view provides the big
picture
Aerial archaeology is so effective for the simple reason that,
paradoxical as it may seem, there are things that can be seen
in a distant view that cannot be seen in a close one.

Examine a newspaper photograph under a strong magnifying glass.
All you see are dots, right? Now imagine yourself about the size
of an ant, standing on the surface of that paper. What chance
would you have of seeing the picture then? At best you would see
only clusters of dots. You'd be too close to the dot pattern to
make any sense of it. However, if you could only get up off the
surface a few feet, and get a vertical view, all the dots would
once again merge into a picture.

An archaeologist standing on the ground is in much the same situation.
There are patterns on the ground around him that he cannot see,
simply because they are too large, he's right in the middle of
them, and he is looking at them practically horizontally. Let's
illustrate this with a real world example, and an almost literal
one at that, if we substitute stones for dots.

In the first photo (20K) we see
a person standing in the midst of what appear to be randomly scattered
stones, or at best perhaps a few places where they seem to be
piled in long rows. There is actually a large pattern of stone
alignments all around that person, but it is not apparent to her
because of its size. In the second
photo (20K), an aerial view of the same location, the true
arrangement of the stones is revealed.

Seen from above, it is obvious that someone has actually aligned
these stones into big squares or grids (probably outlining food
gardens, say archaeologists). Although it was done in prehistoric
times, and weathering over the centuries has scattered the rocks
somewhat, blurring the picture a bit, the overall arrangement
is still clear in the aerial view

Thus, the archaeologist has the opposite problem from that of
the astronomer. An astronomer wants to study things that are too
distant for good viewing, so he must bring them closer and make
them larger, optically, using a telescope. Some things the archaeologist
wants to study, however, are too close for good viewing, and must
be moved father away to gain a more distant and revealing perspective.
Since he can't move his subject (the ground) away from himself,
he accomplishes the same thing by moving himself away from the
ground. He climbs a ladder, or goes up in an airplane, trading
his practically horizontal view for a more vertical one.

And just as the astronomer focuses his telescope on a star by
moving the lenses closer together or farther apart, the aerial
archaeologist in an airplane focuses his view of the ground (and
whatever he is looking at on it) by moving himself closer to or
farther away from it (flying higher or lower). There are certain
kinds of features (prehistoric roads, for example) that show up
best from high altitudes. Details of a buried town, on the other
hand, might best be seen at lower levels.

Another real-world example of what
a more distant and vertical view can reveal is illustrated by
the next two photographs. The remains of a buried city, which
can look like a chaotic arrangement of mounds and hollows at ground
level, will look far different when seen from above:

To summarize, it is simply a distant view of the ground, re-focusing
our view in a larger perspective, that reveals things that are
often undetectable at ground level. That is the secret of aerial
archaeology.

Still to be discussed:

The above discussion covers the data acquisition side of aerial
archaeology. In the next update of the site we will discuss the
other half of the subject: the study and application of the data
acquired (such as formulation of archaeological hypotheses, planning
fieldwork, the making of maps from photographs, etc.), which is
usually done on the ground.